上一片里，向导带你踩了踩地球的薄皮——地壳。可薄皮下面是什么？一大锅又厚又烫的糖浆：地幔。Last leaf, the guide walked you over Earth's thin skin — the crust. But what hides below the skin? A huge pot of thick hot syrup: the mantle.
第 1 步：最厚的一层Step 1: The thickest layer
先看看它有多大——切开地球，你会吓一跳。First, see how big it is — cut Earth open and you will gasp.
地球像一颗夹心糖：薄薄的地壳是糖纸，中间厚厚的橙色糖浆就是地幔。它占了地球体积的 84%。小小的地核，只占一小角。Earth is like a filled candy: the thin crust is the wrapper, the thick orange syrup inside is the mantle. It takes 84% of Earth's volume. The little core is just a small corner.
你可能会问：石头又硬又脆，怎么会像糖浆一样流？You might ask: rock is hard and brittle — how can it flow like syrup?
第 2 步：固态，却会慢慢流Step 2: Solid, yet slowly flowing
地幔是固态的石头，但热得发软。它像锅里的浓糖浆：热的往上走，冷的往下沉。一圈一圈，转得很慢。几百万年，才挪动一点点。The mantle is solid rock, but heat softens it. It moves like thick syrup in a pot: hot rises, cold sinks. Round and round, very slowly. It crawls a little every million years.
糖浆自己打转，和我们有什么关系？关系大了。Syrup swirling by itself — what does that have to do with us? Everything.
第 3 步：驮着板块的传送带Step 3: The belt carrying the plates
地幔顶上有层软软的软流层，像一条传送带。它一动，就驮着上面的板块一起走。大陆漂移，火山地震，全是它推动的。On top of the mantle sits the soft asthenosphere, like a conveyor belt. When it moves, it carries the plates above. Drifting continents, volcanoes, quakes — all pushed by it.
🎮 你来烧这锅糖浆（30 秒）🎮 Your turn: heat the syrup pot (30 seconds)
先拖温度滑块，看糖浆越热流得越快；再过 4 关，说出对流是怎么推板块的。First drag the heat slider — hotter means faster flow. Then clear 4 rounds on how convection pushes plates.
一句话记住它：地幔是地球最厚的一层，像又烫又黏的糖浆；对流推着板块走。Remember it in one line: the mantle is Earth's thickest layer, like hot sticky syrup — and its convection pushes the plates.
占体积 84%，地球最厚的一层84% of Earth's volume — the thickest layer固态但会流：热的上浮，冷的下沉Solid yet flowing: hot rises, cold sinks软流层像传送带，驮着板块漂移The asthenosphere is a conveyor belt carrying the plates
内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.
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